Movable caisson



Jan. 13, 1970 `c;, SAMSEL ETAL 3,489,298

MOVABLE CAISSON Filed July 5, 1967 2 Sheets-Sheet 1 l2 FIG.1 /r

,f 5^ 7A 7N Rf j INVENTORS GERARD sAMsEL, PAUL wERNER, JULIEN KARMAN, ERNEST FERRING BY l mwd/,MM

A'ITORNEYS Jan. 13, 1970 G. sAMsEL ETAL MOVABLE CAISSON 2 Sheets-Sheet 2 Filed July 5. 196'? FIG. 3

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INVENTORS GERARD SAMSEL, PAUL WERNER,

JULIEN KARMAN, BY ERNEST FERRING A ORNEYS United States Patent U.S. Cl. 214-17 11 Claims ABSTRACT F THE DISCLOSURE A relatively large caisson unit to be coupled under gas-tight conditions to a hot cell. The caisson is provided with a removable cover which, in a secured hermetically sealed face to face relation with the cell cover, perfects the opening of the hot cell in such a manner that decontamination of the external surfaces of the two covers is not later necessary.

The invention relates to a caisson functioning as an air lock and which can be hermetically joined to spaces contaminated by radioactive radiation (so-called hot cells).

For safety reasons, hot cells and containers or caissons conneetible thereto are operated with a slight vacuum, particularly if alpha radiation occurs in the cell in addition to beta and gamma radiation. It is necessary in this case to ensure as far as is practicable that no external air ows into the cell and caisson at the connecting position. For example, French patent specification 1,395,783 discloses means for sealingly inserting a closing chamber between two containers, employing inflatable seals. The chamber incorporates a door with which a passage through the chamber and therefore connection between the two containers can be tightly sealed by remotely controlled means. French patent specification No. 1,346,486 furthermore discloses how two containers can be directly coupled to each other without the use of an interposed closing chamber which has to be decontaminated after use. The closure covers of the two containers in this case are sealingly interlocked relative to each other so that they can be removed in common from the door lining without allowing the contaminated container atmosphere, in which the two open covers are disposed, to reach those sides of the cover which, in the closed condition, are positioned on the outside of the container.

This kind of coupling can be constructed without great difficulty for small and light weight containers having round covers and operated by means of the manipulators provided in hot cells. For larger dimensions, for example, in units with a rectangular door opening of 1 rn. width, it is, however, difficult to seal the container relative to the ambient space or to seal the containers relative to each other. Owing to the large weight of the double covers their precise seating cannot be checked or corrected with the manipulator. Moreover, with a cover circumference of several meters it is not easy to obtain a uniform mechanical sealing pressure.

It is the purpose of the invention while overcoming or reducing the aforementioned diiculties, to provide a caisson whose opening, to be coupled under gas-tight conditions to a hot cell, has a large clear width so that experimental structures can be conveyed in their entirety from the caisson into the cell and vice versa. Such a` caisson may also be employed for transferring a person into the hot cell for emergency purposes.

The invention provides a caisson for surrounding an opening, provided with a removable cover, of a hot cell or other chamber, which caisson has means for electing Ffice a seal with the chamber walls around an area containing the said opening, an opening in the caisson within said area for passage into the caisson of the chamber cover, a cover for the caisson opening removable with the caisson, means for securing the two covers together, means for eecting a seal between and around the two covers so secured and means for withdrawing the two covers as a unit with the caisson to provide a passageway between the caisson and the chamber.

The invention further provides the combination of a caisson as just described with a hot cell, the cell having an opening with an outwardly removable cover, the caisson and the cell co-operating to effect a gas-tight seal around the opening with the caisson and cell covers opposed in face to face relation, and the two covers being secured together and sealed together around their peripheries for removal as a unit into the caisson.

More specifically the invention provides a caisson functioning as an air lock which can be hermetically locked onto rooms (eg. hot cells) contaminated by radioactive radiation, characterised in that coupling means are provided with which the caisson can be uniformly pressed onto the cell around an opening therein with a removable cover and that furthermore locking means are provided on the caisson cover with which the said caisson cover and room or cell cover can be mechanically joined, the space enclosed between covers being hermetically sealed in the locked condition by means of seals provided on the circumference of at least one of the covers.

In one form of the invention pivoting arms which rst displace the two interlocked covers perpendicularly to the cover plane and then pivot them into the caisson are provided on the caisson cover for opening the cell. Rolling elements on the cell opening ensure precise guiding and centering thereon of the cover.

The pivoting arms are advantageously constructed as hydraulic or pneumatic jacks to ensure a uniform contact pressure. The pivoting motion is advantageously limited in the closing position by adjustable abutments.

A specific embodiment incorporating these and further features of the invention will now be described, by way of example, with reference to the accompanying FIG- URES l to 4 in which:

FIGURE l is a vertical section through the caisson,

FIGURE 2 shows half of a horizontal section along the line A-A of FIGURE 1,

FIGURE 3 shows to an enlarged scale a detail of a cover joint, and

FIGURE 4 is a view of a pneumatic cover-locking arm.

FIGURE 1 illustrates a mobile caisson in vertical section applied to the opening of a hot cell. The caisson is provided with a steel skin 1, a sealingly inserted inspection window 2, a bogie frame 3 and a cover 4 disposed on the wall opposite to the window for hermetically sealing the caisson by means of a sealing and locking system to be explained by reference to further figures. In the interests of simplifying the description of the invention, electrical, pneumatic and other connections to the caisson have not been described.

On the interior of the caisson, the caisson cover 4 is supported by two hydraulic or pneumatic jacks 5 which are pivotably mounted on fulcrums 6 secured to the internal wall of the caisson. As can be seen from the horizontal section of FIGURE 2, the pivoting motion can be controlled from the outside of the caisson by means of a hand lever 7. A counterweight 8 which extends beyond the fulcrum 6 on the side distal to the cover is connected to the pivoting arm 5 to compensate the weight of the cover. In the closing position shown in the drawing the pivoting arm 5 bears upon an adjustable abutment 9.

A pneumatically operated interlocking mechanism 10, to be explained in detail subsequently by reference to 3 FIGURE 4 and serving for the remotely controlled locking of both covers is disposed on the interior of the caisson cover.

FIGURE 2 also discloses coupling means 11 mounted on the outside of the caisson wall and coupled manually with bayonet apertures 13 appropriately disposed on the wall 12 of the hot cell.

To transfer an object disposed in the caisson into the hot cell it is necessary for the following steps to be effected successively:

(a) The caisson is moved onto the hot cell and locked thereto by means of the elements 11 and 13;

(b) The pneumatic cover-lock 10 for joining the two covers to each other is operated so that the two covers form an integral whole;

(c) The pivoting arms are shortened so that the two covers are retracted into the caisson to a first position of rest designated with the numeral 14;

(d) The pivoting arms are moved by the hand lever 7 from the horizontal into the vertical position, shown in broken lines in FIGURE l and indicated by the numeral 15;

(e) A member 16, which either extends a rail system within the caisson or extends the caisson bottom through the opening into the hot cell, is pivoted into the horizontal (by means of the manipulator of the hot cell);

(f) By means of the hot cell manipulator the object is pulled over the rails 16 into the cell;

(g) The double cover is once again pivoted in front of the opening, the pivoting motion being precisely limited by the stop 9;

(h) The double cover is pneumatically (or hydraulically) driven into the opening;

(i) The two covers are unlocked and the caisson is uncoupled from the container.

As will be explained hereinafter, a sealing system on the circumference of the two covers ensures that the contaminated caisson atmosphere cannot ingress between the two covers, so that there is no need for decontaminating the external surfaces of both covers in the uncoupled condition after each transfer operation.

FIGURE 3 illustrates to a greatly enlarged scale and in detail a section through the closing joint. Sealing between the wall 12 of the hot cell and the cell cover 17 as well as between the wall 1 of the caisson and the cover 4 and finally between the two covers 4 and 17 respectively is ensured by two sealing strips 18 and 19. The rst sealing strip 18 is mounted on the wall of the hot cell and, in the closing position, is in physical contact with the cell cover as well as with the caisson wall. The second seal 19 is mounted in the caisson cover and, in the closing position, is in physical contact both with the cell cover as well as with the caisson wall. When the two covers are removed from the opening, the aforementioned seal 19 also ensures that the zone between covers cannot be Contaminated.

The seals are constructed as gas-filled tubular members. The illustration furthermore discloses that several rolling elements 20 are disposed on the opening of the hot cell on which rolling elements the cover edge can slide to permit self-centering of the cover in the opening. The FIGURE 3 furthermore discloses a safety bolt 21 which is operated from the outside and serves for locking the caisson cover in its closing position for as long as the pneumatic or hydraulic closure of the pivoting arms 5 is ineffective.

The description dispenses with explaining the locking of the cell cover in the cell opening. These locking means function either mechanically, similar to the external caisson locking means, or they may be disposed in the interior of the hot cell and be operated either by the manipulator or by pneumatic means.

The final FIGURE 4 is a plan view of the locking means of FIGURE 1 in the corners of the caisson cover with a pneumatic cylinder 22 which operates a locking arm 23. The said arm locks a bayonet head, rotatably journalled in the caisson cover, in a mating piece disposed in the cell cover.

The caisson according to the invention may have a round or rectangular opening, clear door openings of l m. being perfectly feasible. The caisson according to the invention is therefore suitable for the transfer therein or therefrom of completely assembled test rigs which may be disposed on a flat, mobile table which is not shown. The size of the caisson also permits the transfer of personnel into the cell where such human intervention is necessary in emergency cases. To this end the caisson may have one or more manholes 24 through which personnel may enter into the caisson when the caisson cover is closed. It is known for personnel to don protective clothing whose opening can be engaged in the manhole so as to be hermetically sealed thereto. When the person is within the protective clothing a cupula is placed on said person to seal the manhole whereupon the person within the protective clothing unlocks himself from the manhole frame and is able to move freely in the caisson.

Although the invention has been described by reference to a proven embodiment example this does not by any means represent the only possible embodiment of the invention in all details.

What we claim is:

1. A caisson for surrounding an opening of a chamber wherein the chamber is of the type having a removable cover for sealing its opening, said caisson comprising:

means for effecting a seal with the walls of said chamber around the area containing the opening;

an opening corresponding to and positioned adjacent the opening in said chamber, the opening in the caisson serving to provide a passageway through which may pass the chamber cover;

removable cover means for sealing the opening in the caisson;

means for securing the cover of the chamber to the cover of the caisson;

means for effecting a seal between and around the two covers while said covers are secured; and

means for withdrawing the two covers as a unit with the caisson to provide a passageway between the caisson and the chamber.

2. A caisson as claimed in claim 1 in which the cover withdrawal means operate first to withdraw the unit in a direction perpendicular to the plane of the covers and then to rotate the unit about an axis at right angles to that direction and located within the caisson spaced away from the unit.

3. A caisson forming an air lock which is capable of being hermetically locked onto a chamber -contaminated by radioactive radiation, wherein said chamber is of the type having an opening therein and a removable cover for sealing the opening, said caisson comprising:

an opening corresponding to and positioned adjacent the opening in said chamber;

a removable cover for sealing the opening in the caisson; coupling means for iixedly attaching the caisson to said chamber with the respective openings in alignment;

locking means on the caisson cover for mechanically joining said caisson cover and said chamber cover; and

sealing means on the surface of at least one of said covers for hermetically sealing the space between the locked covers.

4. A caisson according to claim 3 and further comprising at least one pivoting arm for mounting the caisson cover so that the caisson cover, once locked to said chamber cover, is first displaced at right angles to the cover plane and, when the chamber is opened, is then pivoted.

5. A caisson according to claim 4, whereby the pivoting alms are Constructed as hydraulic jacks.

6. A caisson according to claim 4, whereby the pivoting arms are constructed as pneumatic jacks.

7. A caisson according to `claim 4 and further comprising adjustable abutments for providing stops for said pivoting arm.

8. A caisson according to claim 3 and further comprising at least one pair of guiding and supporting means disposed on the caisson oor and having extension pieces which can be hinged into the chamber for supporting tables or other supports traversable thereon.

9. A caisson according to claim 3 and further comprising a travelling bogie for mounting said caisson.

10. A caisson according to claim 3 and further comprising gas-filled tubular seals functioning as sealing means.

11. A caisson according to claim 3 and further cornprising an extension with at least one manhole into which protective clothing for a man can be engaged.

References Cited UNITED STATES PATENTS ROBERT G. SHERIDAN, Primary Examiner 

